Nitrogen-water Relationships of Onions Grown on Organic Soil1

Field studies with onions (Allium cepa L. cv Monarch) were conducted in 1980 and 1981 to compare preplant-banded sulfur-coated urea (SCU) with preplant-banded and split applications of urea. Treatments were evaluated at two N rates, 56 and 224 kg·ha−1. Root NO3-N and soil NO3-N concentrations in bed centers indicated slower release of N from SCU than from urea. Nevertheless, total and large bulb (> 76 mm in diameter) yields and N uptake in onion bulbs and leaves from SCU were significantly higher under low-N conditions than with preplant urea, but did not differ significantly from split urea treatments.

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“…Adequate N was reported to hasten onion maturity (16). However, high N late in the season was reported to delay maturity of bulb onions (24).…”

Section: Maturity2mentioning

confidence: 99%

Sulfur-coated Urea as a Slow-release Nitrogen Source for Onions

Brown

Hornbacher

Naylor

1988

J. Amer. Soc. Hort. Sci.

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Storage Life of Field-Grown Garlic Bulbs (Allium sativum L.) as Influenced by Nitrogen and Sulfur Fertilization

Bloem

Haneklaus

Schnug

2011

J. Agric. Food Chem.

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The most important active compound in garlic is alliin. Sulfur (S) fertilization was shown to significantly increase the alliin concentration in garlic cloves, while high nitrogen (N) levels had an adverse effect. The effect of graded N and S application on the storage life of garlic has been paid little attention so far. A bifactorial field trial with 4 levels of N and S was conducted in a randomized block design. At harvest, 40 bulbs per treatment were stored under terms comparable to the storage conditions in average households (20 °C, dry, and dim) for 83 days. Every 3 weeks, samples were analyzed for their alliin and water content. The alliin concentration in peeled garlic cloves increased during storage from on average 9.2 mg g(-1) dry weight at harvest to 21.4 mg g(-1) dry weight after 83 days of storage. S fertilization increased the alliin concentration by a factor of 2.3 from 11.4 mg g(-1) in the control treatment to 26.6 mg g(-1) dry weight at the highest S level of 45 kg ha(-1) after 83 days of storage. N fertilization decreased by a trend of the alliin content. Fertilizer rates had only a minor influence on water losses from bulbs at short-term storage. After 83 days of storage, water losses were by trend lower at higher S levels, and this relationship proved to be significant when no N was applied. Best quality in terms of high alliin contents was obtained during the entire storage time at an S level of at minimum 30 kg ha(-1) S if no N was applied. The results show that the physiological S demand of 15 kg ha(-1) S for optimum yield is lower than the S requirement of 30 kg ha(-1) S for a longer storage life.

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